While various types of surgical snares have been protightening of the loop and avulsion of the tissue for their --operation This tearing of the tissue often results in incomplete removal and an irregular wound that often produces additional complications. One of the principal objects of the present invention is to provide a surgical snare which has all of the advantages of more conventional instruments and further provides a cutting action that wiil reduce the tearing of the tissue so as to produce a cleaner wound.

-Another object of the present invention is to provide a surgical snare that is particularly suitable for removing relatively small sections `of animal tissue with a high egree of accuracy.

A further object of the present invention is to provide :a surgical snare that can be used for removing tissue that 4g'is deeply situated.

` A still further object of the present invention is to provide a surgical snare of the type described that is spring-actuated so as to cleanly cut and remove animal tissue in a quick and efficient manner.

All of the foregoing and still further objects and advantages of this invention will become apparent from a study of the following specification, taken in connection with the accompanying drawing, wherein:

Fig. 1 is a longitudinal cross-sectional view of a surgical snare made in accordance with the present invention, with the parts in the position assumed following the use of the instrument.

Fig. 2 is a view similar to Fig. l, with the parts in initial position ready for use.

Fig. 3 is a greatly enlarged side elevational view, with parts broken away, of certain parts of the snare shown in Figs. l and 2.

Referring now to the drawing, and more particularly to Fig. l thereof, a surgical snare 10 made in accordance with the present invention is shown to include a main barrel portion 11 having a central longitudinal bore within which a plunger member 12 is supported for reciprocating longitudinal movement. A closure cap 13 having portions overlying the central longitudinal bore of the main barrel member is threadingly connected to the rear end of the main body member and thus limits the outward movement of the plunger 12 in that direction. The outwardly extending stem 14 of the plunger has a central longitudinal bore and is provided at its engages a threaded shaft 17 which is supported within the longitudinal bore of the stem. Secured to the outermost end of the threaded shaft 17 is a pressure plate 16 against which linger pressure may be exerted in order to depress the plunger 12 toward the position shown in Fig. 2.

The base 18 of a surgical needle 19 is secured to the inner end of the threaded shaft 17 for reciprocating "ice 2 longitudinal movement with the plunger 12, stem 14, and threaded shaft 17. A compression coil spring 20 encircles the needle 19 and is seated at one end upon the inner end of the plunger 12 and at the opposite end upon a shoulder formed by the interior of the main body portion 11. This spring normally urges the plunger 12 toward the retracted position shown in Fig. 1, while a detent in thel form of a stop pin 23 is engageable with an annular groove 12 at the inner end of the plunger 12 to secure the plunger in the depressed position shown in Fig. l, against the action of this spring. This stop pin 23 is normally urged toward the locking position within the transverse bore 23 through the housing wall by means of the supporting spring plate 26. However, an arcuate lift arm 24 carried by a longitudinally movable slide actuator 25 is operative to engage beneath the head of the stop pin 23 to lift it out of the path of movement of the plunger 12 to disengage it from the groove 12 to permit the plunger to be moved to the retracted position shown in Fig. l by the action of the springy 2t). Air relief ports 21 at opposite ends of the main body portion permit the air to enter and escape so as to prevent pneumatic interference with the travel of the plunger.

A hollow head 27 is frictionally secured to the tapered base 22 at the front end of the main body portion 11 and further supports a hollow extension 28. yThe wire snare loop 30 is formed from a length of very fine surgical wire that has one end secured Within a longitudinal groove 29 formed in the outer end of the needle 19, such as by solder 31. The opposite end 32 of this length of wire is frictionally secured between the mating portions of the tapered base 22 and the head 27, with the central portion of the loop extending outwardly through a sleeve 33 carried by the outer end of the hollow extension 28.

It will be noted that the needle 19 moves relative to the outermost end of the sleeve 33, within the hollow extension 28 and sleeve 33, thus imparting motion to but one end of the length of wire forming the snare loop 3d. The other end 32 of the wire is held securely in place by the wedge type engagement described. Thus, as the plunger 12 is ejected by the action of the spring 2d, in response to the release of the detent stop pin 23, the loop is constricted by the movement of one end of the wire only. This has the eiect of drawing the wire across the surface of the tissue to produce a cutting action as the loop is constricted during the entire retracting movement of the plunger 12. This action can thus be readily distinguished from other types of snare action in which both ends of the snare loop are moved simultaneously so as to merely reduce the size of the loop without the relative movement of the wire across the surface of the tissue.

ln actual use, the plunger is moved to the depressed position shown in Fig. 2, against the action of the spring 20, in which position it Amay be held by the detent 23 when the actuator plate 25 is moved to the illustrated position. The loop 30 of the snare is then enlarged and ready for use so that after it is placed around the tissue to be removed, forward movement of the actuator plate 25 to the position shown in Fig. l is operative to retract the plunger 12 to produce the aforementioned cutting action of the wire and to constrict or reduce the size of the loop 30, thus removing the tissue. By rotating the pressure plate 16 and threaded shaft relative to the lock nut 15, the extent of forward and rearward movement of the needle 19 can be altered to adjust the size of the respective enlarged and constricted snare.

While this invention has been described with particular reference to the construction shown in the drawing, it is to be understood that such is not to be construed as a imparting limitations upon the invention, which is best dened by the claims appended hereto.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. A surgical snare comprising in combination, a main body member having a front end anda rear end, a plunger member slidably supported withinsaid rear Aend of said main body member for reciprocating longitudinal movement between a retracted position and a depressed position relative to said rear end of said main body portion, a spring normally urging said plunger toward said retracted position, releasable means for securing said plunger in said depressed position against the action of said spring, a wire snare loop extending outwardly through said front end of said main body member having one end connected to said plunger and the other end connected to the vinterior of said main body member.

2. A surgical snare comprising, in combination, a main body member having a front end and a rear end, a plunger member slidably supported within said rear end of said main body member for reciprocating longitudinal movement between a depressed position and a retracted position relative to said rear end of said main body portion, a wire snare loop extending outwardly through said front end of said main body member having one end connected to said plunger and the other end connected to the interior of said main body member.

3. A surgical snare as set forth in claim 2, wherein said front end of said main body member includes a sleeve, and said loop has a portion extending outwardly through said sleeve.

4. A surgical lsanare as set forth in claim 3, further 4. comprising controllable means for effecting movement of said plunger toward said retracted position to constrict said portion of said loop extending outwardly of said sleeve.

5. A surgical snare as set forth in claim 4, wherein said controllable means comprises a spring acting between said plunger and said main body member.

6. A surgical snare as set forth in claim 5, further comprising stop means releasably securing said plunger in said depressed position against the action of said spring.

7. A surgical snare as set forth in claim 6, wherein stop means comprises a detent slidably carried by one of said main body and plunger members for movement in a direction transversely of the path of movement of said plunger, an indent in the other one of said members for releasably receiving one end of said detent, and manually operable means carried upon the exterior of said main body member for disengaging said detent from said lindent.

8. A surgical snare as set forth in claim 7, further comprising spring means normally urging said detent in the direction toward said indent.

9. A surgical snare as set forth in claim 8, wherein saidy indent is in said plunger member, and said detent is slidably supported by said main body member.

References Cited in the file of this patent UNITED STATES PATENTS Kingman et al. Dec. 16, 1924 Wright Sept. 21, 1926 a